1. Field of the Invention
The present invention relates to a method of waterproofing wood and simultaneously providing stain resistant and decay resisting properties thereto and to compositions which are employed in achieving these objectives.
2. Description of the Prior Art
The beneficial properties of wood have been employed advantageously in numerous end uses for centuries. For example, wood has been used in the construction of buildings and building products, such as windows and doors. Wood has been employed in view of its relatively high strength, ease of processing and handling, and relatively low cost. Wood, however, has the negative aspect of being susceptible to deterioration under the influence of moisture, microorganisms, and insects.
It has been known to treat wood with protective coatings as by applying paint to exposed wood surfaces, for example.
It has also been known to treat wood with preservatives, such as copper-chromium-arsenic solutions (CCA), pentachlorophenol and creosote oil with application being effected by pressure impregnation. It has also been known to treat wood through immersion in solutions containing salts of chlorinated phenols. These chlorinated phenols, however, have become of great concern from a human safety and environmental hazard standpoint.
The United States millwork industry requires that wooden parts intended to be used for window manufacturers must be treated with a water repellant wood preservative solution. This requirement is set forth in the National Wood Window and Door Association Specification NWWDA I.S. 4-81. Traditionally, most millwork preservatives were carried in a mineral spirits solvent to facilitate penetration into the wood and drying of the treated wood prior to painting or cladding. Recent amendments to the United States Clean Air Act, however, have caused millwork manufacturers to look for ways to reduce the solvent emissions from their facilities. This has led to increased interest in development of water borne millwork preservative systems.
It has been known to employ didecyldimethyl ammonium chloride to resist wood damaging fungi and termites. See, generally, Chemical Abstracts, Vol. 87, No. 87:103500p, Butcher et al. (1987).
It has also been known to employ 3-iodo-2-propynyl butyl carbamate as an active ingredient against fungi. See, generally, Chemical Abstracts, Vol. 92, No. 92:75897f, Singer (1980).
U.S. Pat. No. 4,950,685, the disclosure of which is incorporated herein by reference, provides a synergistic wood preservative composition which has a quaternary ammonium compound and 3-iodo-2-propynyl butyl carbamate. It also discloses certain preferred quaternary ammonium compounds, such as didecyldimethyl ammonium chloride, tri-methyl-coco-ammonium chloride and dimethyl-di-coco-ammonium chloride. This disclosure provides for improved stain resistance in wood, as well as certain additional beneficial properties.
While it has been known to make advantageous use of such prior art quaternary ammonium compounds, they have not been readily combinable with known waterbased waterproofing compositions usable in wood. The problem has arisen due to the quaternary ammonium compounds being cationically charged molecules which are extremely hydrophilic and have, in fact, served as effective wetting agents. These properties are obviously undesirable for a composition wherein water repellant properties are being sought.
U.S. Pat. No. 4,615,739 discloses an oil-in-water-in-oil coating material which employs polysaccharide, which is a hydrated starch. It is said to have a non-aqueous continuous phase and an aqueous discontinuous phase and is said to be usable as a coating which is said to have superior weathering, wetting, adhesion and stability characteristics. There is no wax emulsion or quaternary ammonium compound employed.
U.S. Pat. No. 4,432,797 discloses a water-based stain which is said to resist pigments settling prior to use. The formulation includes a film-forming resin, pigment, water thickener, and water. The film-forming resin is disclosed as being an acrylic resin.
U.S. Pat. No. 4,866,106 discloses an antifouling coating composition which includes a non-metallic algicide which is a quaternary ammonium compound and a non-metallic algicide. See, also, U.S. Pat. Nos. 4,990,547 and 5,096,488.
In spite of these known materials, there is lacking a method and associated composition for effectively resisting undesired deterioration of wood by combining waterproofing properties with other desired preservative properties, such as anti-stain and anti-fungal properties.